1. Field of the Invention
The invention is directed to a stretchable material suitable for use in flashing applications to prevent water intrusion through openings in building structures such as windows and doors.
2. Description of the Related Art
Materials that are installed in openings in building structures to provide protection from water intrusion are known as flashing. Flexible self-adhering flashing materials, sometimes referred to as flashing tapes, provide protection by covering building framing and sheathing. Flexible flashing materials rely on the underlying building framing for primary structural support.
The stretch recoverable flexible flashing material disclosed in PCT application WO 0181689A (Waggoner et al.) comprises a laminate of a nonwoven layer bonded to a waterproof layer with an adhesive, including an array of spandex fibers between the nonwoven layer and the waterproof layer. The spandex fibers provide elasticity to the flashing material. The spandex fibers have strong elastic recovery that results in a retraction force when the flashing is installed. PCT application WO 0181689A discloses that preferably the flashing material has a stretch recovery of at least 90%. The retraction force creates a shear force that opposes the force of the adhesive that holds the flashing in place. This force is strongest over three-dimensional installations such as over windowsills, where the flashing is adhered to surfaces in three dimensions, i.e., a horizontal surface sill surface, a vertical jamb surface and the surface of the planar substrate forming a wall. In such installations, the product may have the tendency to pull back from the planar substrate of the wall, therefore the manufacturer's recommended practice when installing the flashing is to drive mechanical fasteners such as nails or staples through the flashing to ensure that the flashing remains securely in place while the adhesive strength develops.
It is desired to have a flashing material with a lower retraction force at the desired level of extension, obviating the need for mechanical fasteners to hold the flashing material in place. This is especially helpful in the case where the substrate that the flashing is adhered to is a rigid material such as concrete block or masonry where it may be difficult to install the fastener. Other known flashing products include creped self-adhered flexible flashing products Protecto Flex™ produced by Protecto Wrap Company (Denver, Colo.), and Contour™ flexible tape produced by Ludlow Coated Products (Doswell, Va.). These products comprise a creped film laminated to a bulk adhesive layer. None of these products has sufficient levels of extensibility and recovery to cover the surfaces of a three-dimensional windowsill and remain in place in the desired location.